Letters contaminated with weapons-grade Bacillus anthracis (anthrax) spores passed through the United States Postal Service (USPS) after Sep. 11, 2001. Over 16 cases of documented infections and several deaths have been directly attributed to such letters. By November 2001, over 32,000 individuals in the United States were taking antibiotics prescribed by physicians specifically as a prophylactic measure to combat a potential exposure to anthrax contaminated mail. Multiple mail processing facilities, and the equipment within those facilities, were contaminated by exposure to what appears to have been a statistically small number of intentionally contaminated letters.
It should be noted that the USPS relies heavily on automation to process over 550 million pieces of mail every day. Numerous advanced machines are thus employed for the handling of postal mail by both the USPS and businesses. One well-known manufacturer of such devices is Pitney Bowes (www.pitneybowes.com). Machines designed for processing mail have a range of envelope-handling capabilities, including stuffing, sealing, franking, and opening. The scope of such mail processing equipment ranges from desktop versions designed for use in a small office to very large industrial versions intended for use in a major corporate setting, or in a governmental postal facility. With respect to the anthrax contaminated letters mailed within the United States during September 2001, it appears that such mail processing equipment may have contributed to the cross-contamination spread of anthrax spores to mail received by many others than just the intended recipient of an intentionally anthrax-laced letter.
It appears that the very small size of the anthrax spores enabled at least some spores to escape from envelopes during mail processing, even while the envelopes remained sealed. Postal grade envelopes are not intended to be airtight, and processing such anthrax laced envelopes with mail handling equipment appears to have applied sufficient pressure to force spores out of such envelopes, so that the anthrax spores were released during mail processing, rather than only when the anthrax-laced mail was actually opened at its intended destination. The released anthrax spores then contaminated the mail processing equipment, and apparently cross-contaminated additional items of mail.
At the present time, there exists no mail processing equipment with the capability to screen mail for anthrax contamination, or other types of biological or chemical contaminants. Unfortunately, anthrax is not the only agent of concern. It has been suggested that the smallpox virus, which has been virtually eradicated in the natural environment, could be cultivated and used as an agent of terror in much the same fashion as the anthrax mailings were. Extremely toxic chemical agents such as ricin, might also be disseminated through the mail.
To address these issues, it has been suggested that all items of mail should be exposed to levels of radiation sufficient to kill such biological agents before the mail is otherwise processed and distributed, thus eliminating the danger posed by such biological agents.
While the techniques for mail irradiation are fundamentally similar to those used for the irradiation of certain agricultural products to reduce spoilage and kill pests, and can remove the danger presented by such biological agents, the equipment used for irradiation cannot detect the presence of such agents. From a security and law enforcement perspective, it is highly desirable to know of the occurrence of such events, even if irradiation has reduced or eliminated the threat. For example, early detection of intentionally contaminated mail will greatly aid law enforcement agencies in any investigation into the source of such contamination. While contaminated mail can be detected when it is opened at its ultimate destination, it is clearly much more preferable to detect and remove such mail from the postal system, even if irradiation has eliminated or reduced the risk of harm caused by the contamination.
It would therefore be desirable to provide a method and apparatus to identify mail within the postal system that is contaminated with anthrax spores, or other biological agents. While analytical devices and methods are available for detecting anthrax spores, such equipment and methods are not readily adapted for incorporation into high volume mail processing equipment.
Air monitoring equipment can be used in detecting contaminants. For example, a handheld, portable air monitoring system is described in commonly assigned U.S. patent application Ser. No. 09/775,872, filed on Feb. 1, 2001 and entitled BIOLOGICAL INDIVIDUAL SAMPLER. The application describes a device that can detect trace amounts of contamination within a volume of air that is sampled by the device. The device rapidly obtains a sample that can then be tested using analytical techniques appropriate to the suspected contaminant. For suspected anthrax contamination, the sample can either be taken to a lab for analysis, or can immediately be tested using commercially available (albeit somewhat less sensitive) “test strips.” Such a system, however useful for air monitoring of a room or a disaster area, is not nearly as useful for detecting anthrax or other contaminant agents within mail. While a sample of air from or around a specific piece of mail could indeed be collected and tested with the device, the sheer volume of mail passing through the USPS makes widespread use of such equipment inadequate for testing the majority of the mail passing through the USPS to detect the presence of biological agents.
It would thus be desirable to provide a method and apparatus for detecting potentially harmful biological agents within the USPS that can achieve the following objectives:
1. The system should effectively process very high volumes of mail daily (i.e., from tens to hundreds of thousands of pieces of mail per day);
2. The system should be effective in detecting contaminated or suspect letters. Most important is the ability to detect anthrax, but the system should also be able to detect other biological and chemical agents;
3. The system must have an extremely low rate of false negatives (i.e., ideally, the system should not “miss” ANY contaminated letters);
4. The system should also have an extremely low rate of false positives (i.e., even one false positive in 500 million letters processed may be unacceptably high, given the disruption a positive indication of biological contamination is likely to generate);
5. The system should be relatively low in cost, resulting in a minimal increase in postal rates, preferably on the order of a penny per letter or less; and
6. The system for screening mail must be compatible with existing mail processing technology and operations and must protect personnel and facilities from contamination.
The prior art does not provide a system for simultaneously processing and analyzing high volumes of mail to detect biological threats that is capable of achieving even a few of the above objectives. Clearly, there is an immediate need for such a system to protect workers in the USPS and to protect all of the citizens of this country who depend upon and use the USPS.